Electrodeposition on non-conductive surfaces

ABSTRACT

A process for metalizing a non-conductive substrate wherein the substrate is coated with an organic polymer-carbon black mixture, having a volume resistivity of less than about 1,000 ohmcentimeters, the surface of the mixture is caused to contain sulfur and the thus treated substrate is placed as a cathode in a nickel, cobalt or iron plating bath to cause a rapid spread of metal across the thus treated surface.

United States Patent [1 1 Luch 111] 3,865,699 [451 Feb, 11, 1975ELECTRODEPOSITION ON NON-CONDUCTIVE SURFACES [75] Inventor: Daniel Luch,Warwick, NY.

[73] Assignee: The International Nickel Company,

Inc., New York, NY.

[22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,410

[58] Field of Search 204/20, 30; 117/201, 47 A, 117/47 R; 252/510, 511

[56] References Cited UNITED STATES PATENTS 1,624,575 4/1927 Biddle204/4 2,551,342 5/1951 Scholl 204/30 2,551,343 5/1951 Scholl 204/302,551,344 5/1951 Scholl 204/30 2,732,020 1/1956 Scholl 204/30 2,776,2531/1957 Scholl 204/20 3,523,875 8/1970 Minklei 117/201 3,619,382 11/1971Lupinski 204/38 B FORElGN PATENTS OR APPLlCATlONS 196,063 4/1923 GreatBritain..,.. 2.04/20 534,818 3/1941 Great Britain 204/20 10/1946 Canada204/20 OTHER PUBLICATIONS Chemical Abstracts, Vol. 40, 2673.

Industrial Carbon, Mantel], Van Nostrand, 1946, p. 87.

The Electrodeposition of Iron, A. D. Squitero Products Finishing.

Primary Examiner-T. M. Tufariello [57] ABSTRACT A process for metalizinga non-conductive substrate wherein the substrate is coated with anorganic polymer-carbon black mixture, having a volume resistivity ofless than about 1,000 ohm-centimeters, the surface of the mixture iscaused to contain sulfur and the thus treated substrate is placed as acathode in a nicke1, cobalt or viron plating bath to cause a rapidspread of metal across the thus treated surface.

29 Claims, 2'Drawing Figures ELECTRODEPOSITION ON NON-.CONDUCTIVESURFACES The present invention is concerned with electrodeposition andmore particularly with electroplating of a non-electrically conductivesubstrate.

BACKGROUND OF THE INVENTION Since the start of electroplating, a largenumber of proposals have been made with respect to electroplating onnon-electrically-conductive substrates ranging in size and shape acrossthe gamut of leaves, flowers, baby shoes, plastic knobs, bottle tops,molded plastic parts for automotive usage and uncounted other practicaland decorative structures. Basically, two processes have been used. Thefirst process involves the coating of the non-conductive object with anelectrically conductive lacquer followed by electroplating. The secondprocess involves sensitizing the non-conductive object, chemicallydepositing a metal on the sensitized surface and thereafterelectroplating the thus metallized surface.

The two generally available processes as practiced in the prior art havecertain disadvantages. Because of high loadings of conductive pigmentssuch as graphite or metal, prior art conductive lacquers are generallyvery weak and thus constitute a weak link in the ultimate electroplatedstructure. A variation of the lacquer process which involves coating thetacky lacquer surface with graphite again produces very weak. bondsbetween electrodeposited metal and the lacquer much like the ephemeralbond produced between graphitized wax and electrodeposited metal in theelectrotyping process. If lower pigment loadings are used in aconductive lacquer to give greater strength in the lacquer, the rate ofinitial metal coverage of the article during electroplating is radicallydecreased necessitating the use of multiple electrical contact points onthe object to be plated or allowance of a long time for metal coverageand consequent uneven plating thicknesses.

The second process as generally practiced by the prior art, can achievegood results but only at a cost of employing a large number ofindividual processing operations carried out with very great care byskilled per sonnel. Furthermore, because the underlying chainicallydeposited metal can be different from metalsubsequentlyelectrochemically deposited, there is a good chance of forming anelectrochemical couple between the two even when, nominally the metalsare the same. Thus the possibility of accelerated, localized corrosionexists wherever and whenever the outer electrodeposited layer is notcontinuous.

Recently, U.S. Pat. No. 3,523,875 to Minklei and U.S. Pat. No. 3,682,786to Brown et al. have issued. These recently issued patents are worthy ofdiscussion because, superficially they. might appear to resemble theprocess of the present invention. Minklei proposed to treat a plasticsurface with an aqueous solution of alkali metal sulfide followed bycontacting the treated surface with a metal salt prior toelectroplating. Brown et al. proposed contacting a plastic surface witha solu-. tion or dispersion of sulfur in an organic medium andcontacting the treated surface with an aqueous solution of cuprous saltprior to plating. In both instances, the proposals involve the formationof a metal sulfide on the plastic surface and not the type ofmetal-polymer bond, which, as will become apparent from the subsequentdescription, is formed by virtue of'the process of the presentinvention.

OBJECTS It is an object of the present invention to provide a processfor electrodepositing metal on non-electricallyconductive substrates.

It is another object of the present invention to provide a process forelectrodeposition on substrates which are not amenable to ordinaryelectrodeposition techniques.

Other objects and advantages will become apparent in light of thefollowing description taken in conjunction with the drawing in whichFIG. 1 depicts electrodeposit growth obtained in accordance with thepresent invention and;

FIG. 2 depicts undesirable electrodeposit growth obtained when anessential requirement of the process of the present invention isomitted.

DESCRIPTION OF THE INVENTION Generally speaking the present inventioncontemplates a process wherein at least part of a substrate forelectrodeposition comprises or is coated with an adherent layer of amixture of an organic polymer and an electrically conductive carbonblack of such proportion so as to have an electrical resistivity of lessthan about 1,000 ohm-centimeter; at least the exposed surface of thelayer is caused to contain an effective amount of sulfur, and the thuscoated object is then introduced into a nickel, cobalt, or iron platingbath as the cathode to cause rapid deposition of metal across the coatedsurface. Thereafter the metal coated object can be subjected to furtherelectrodeposition in ways well known to those skilled in the art.

The polymer used along with conductive carbon black in the coating layer(and which. may also constitute the substrate) is, advantageously amember of the group of organic polymers which readily react withmolecular sulfur or a sulfur donor of the type described herein.Advantageous polymers for use in the process of the present inventioninclude hydrocarbonaceous and substituted hydrocarbonaceouselastomerssuch as natural rubber, a polychloroprene, butyl rubber, chlorinatedbutyl rubber, polybutadiene rubber, acryloni trile-butacliene rubber,styrene-butadiene rubber, etc. These elastomers-are unsaturated andreadily combine with molecular sulfur through either unsaturatedlinkages in the carbon skeletal structure of the polymer or throughactivated sites on the polymer structure associated with unsaturatedlinkages or pendant substituent atoms. Another advantageous type ofpolymer for use in the process of the present invention is anethylenepropylene terpolymer comprising a saturatedpoly-ethylene-propylene main chain having unsaturated groups derivedfrom non-conjugated dienes, e.g., hexadiene, dicyclopentadiene etc.,pendant from the main chain. Such a terpolymer is readily vulcanizedwith sulfur. Other polymersusefull in the process of the presentinvention include essentially saturated polymers such as polystyrene,polyvinyl chloride, polyurethane etc., which apparently possess activesites for reaction with sulfur. While polyethylene (and similar polymersof limited solubility) are not readily suited for use in coatingformulations, it has been found that milled and molded polyethylenecompositions containing carbon black and a sulfur donor canadvantageously be employed in the process of the present invention.Undoubtedly some organic polymers, for example, perhaps,polytetrafluoroethylene are too inert to react with sulfur and thesepolymers are excluded from the ambit of the present invention. However,the great bulk of normally used organic polymeric materials appears tobe useable in the process of the present invention.

Of those polymers which react with sulfur, those having elastomericcharacteristics e.g., rubbers, elastomeric polyurethane etc., areconsidered to be advantageous when used as a coating covering a rigidbase and overlied by the deposited metal, because an elastomer has theability to dampen stress concentrations which can result in failure ofthe deposited coating upon exposure to applied stress or thermalcycling. In addition, with most elastomers, the carbon black includedfor the purpose of providing a proper degree of electrical conductivityacts as a reinforcement agent to improve the physical characteristics ofthe elastomer. Further factors which make elastomers most advantageousinclude rapidity of metal coverage and relatively low cost of materials.Among the elastomers, the unsaturated elastomers are deemed to be themost advantageous.

Those skilled in the art will appreciate that in the foregoingdescription of polymers operable in the process of the present inventionthe examples given are merely illustrative and that many other polymericand copolymeric materials and mixtures can be used in place of thespecifically mentioned substances. For example, very often in rubberformulations amounts of compatible non-elastomeric resins are includedfor various purposes. Polymers other than rubber can, and often arecompounded with plasticizers in order to obtain a product havingflexibility. Such compounded materials as well as copolymers and mixedpolymers are operable for purposes of the present invention.

When as is always advantageous the exposed surface ofthepolymer-conductive carbon black composition is caused to contain sulfurit is possible that the sulfur initially attacks the polymer chain atactivated positions, to provide activated sites for bonding of nickel tothe polymer. Regardless of the theoretical explanation however,applicants experiments have shown that when nickel deposits are made inaccordance with the teachings of the present invention very strong,highly useful metal to organic bonds are formed very strong, highlyuseful metal to organic bonds are formed very rapidly on polymer-carbonblack surfaces. It is important to avoid overcuring of a polymer withsulfur (or other curative) prior to plating. It appears that apolymer-sulfur-metal bond can occur with most polymers as long asactivated sites on the polymer chain exist. Heavy curing, especially insulfur monochloride will remove these sites from an unsaturatedelastomer causing poor plating both as to speed of coverage and as toadherence of the metal. I

The exposed surface of the polymer-carbon black plating substrate cancontain sulfur by inclusion of sulfur in the whole mass of the platingsubstrate or by enriching the exposed surface with sulfur.

Normally. a plating substrate containing an unsaturated polymericelastomer will contain about 0.5% to about 5% of sulfur based uponweight of elastomer in order to permit curing of the elastomer. Whenagents other than sulfur or sulfur compounds are used for curing theexposed surface of the elastomer can be enriched in sulfur by contactingthe surface with a solution containing elemental sulfur or by exposingthe surfaces to a sulfur-containing vapor e.g., the vapor of sulfurmonochloride (S Cl The plating substrate will normally containingredients other than sulfur, elastomer and conductive carbon blacksuch are normally included in rubber compositions. Such otheringredients include vulcanization accelerators and modifiers,antioxidants and similar types of materials which have been found to beuseful in rubber technology. For best results, particularly with respectto adhesion of electrodeposited metal all ingredients should be limitedin amount to amounts which will be permanently soluble in the curedelastomer at normal temperatures i.e., about 25C.

Plating substrates used in the present invention usually contain carbonblack and polymer in weight ratios of about 0.2 to about 1.5 (conductivecarbon black to polymer) although somewhat higher or lower weight ratioscan be used. It is usually more advantageous to employ weight ratios ofconductive carbon black to polymer in the range of about 0.5 to L0. Ithas been noted with coatings on non-electrically conductive substratesthat speed of coverage of polymer-carbon black surfaces becomes very lowat very high loadings of carbon black indicating that a minimum surfaceconcentration of polymer is necessary not only for attaining mechanicalstrength but also forpurposes of facilitating the metal spreadingmechanism of the invention. Because carbon blacks vary greatly dependingupon sources and methods of manufacture, it is not practical to specifywith more precision the relative amounts of polymer and carbon blackrequired in accordance with the present invention. In addition tovariations involved in different types of carbon black, difference indispersion conditions when compounding with polymer can also introducevariations in the polymer-carbon black mixtures. For example, if anacetylene black sold by Shawinigan Products Corp. of Englewood Cliffs,N.J., is milled with an elastomer in a Banbury-type mill, it is likelythat at least part of the chain-like structures of the acetylene blackwill be broken. On the other hand using less agressive mixingtechniques, the chain structure will be retained. Consequently, thecomposition milled in the Banbury mixer will exhibit a higher volumeresistivity than will a composition milled in solution form in a blenderevent though the loading of the carbon black is the same. Thus forpurposes of the invention, the criterion of operability of a particularpolymer-carbon black mixture is the electrical volume resistivity. Asstated hereinbefore, the volume resistivity must be less than aboutl,000 ohm-centimeters and more advantageously is less than about 10ohmcentimeters. Ordinarily it is neither possible nor desirable toobtain polymer-carbon black mixtures having volume resistivities lessthan about 1 ohmcentimeter. At such low resistivities, the strength ofthe polymercarbon black mixture is low. Optimum results have beenobtained using conductive carbon blacks made from acetylene such as soldby Shawingan Products Corporation under the trade designation AcetyleneCarbon Black. Another commercially available conductive carbon blackwhich possesses relatively high resistance to mechanical breakdownduring milling with a polymer is sold by Cabot Corporation under thetrade designation of Vulcan XC72. If desired, mixtures of conductive andnon-conductive carbon blacks can be used provided that the finalpolymer-carbon black product has a volume resistivity in the range setforth hereinbefore. In some instances the proper volume re sistivity canbe achieved in polymer-carbon black compositions which are made entirelywith non-conductive carbon blacks for example, furnace blacks. Suchcompositions ordinarily do not have adequate electrical characteriticswhen used as coatings and dried on a substrate. However, thesecompositions may have adequate characteristics for use as molded,extruded or like-formed shapes which can be treated electrochemically inaccordance with the present invention without a separate preliminarycoating step.

The rate of coverage of nickel cobalt or iron on a cathode having asurface of polymer-carbon black mixture in accordance with the presentinvention extending from a point of contact with an electronic conductor(e.g., a metal) is dependent at least upon the resistivity of themixture, the sulfur content at the mixture surface, the applied voltageacross the anodeelectrolyte-cathode circuit; and the nature of thepolymer. Generally speaking in accordance with the present invention theminimum rate at which nickel spreads across the cathode surface at avoltage of 3.0 volts is about 0.5 centimeter per minute (cm/min). Aseries of polymer-acetylene black compositions were made containing 100parts by weight of polymer and 50 parts by weight of the carbon black.The compositions devoid of sulfur were coated on an ABS panel having ametal contact point at one end. In a first series of tests the panelswere immersed in a Watts type nickel plating bath as cathodes at avoltage of 3.0. The rate of nickel coverage was measured. In a secondseries of tests, the panels were dipped in a solution of 1% (by weight)of sulfur in cyclohexane, removed and the cyclohexane allowed toevaporate prior to electrolytic treatment in exactly the same manner aswas the first series. The results of these tests are set forth in TableI.

TABLE I Table I shows that a very small amount of sulfur incorporated inthe exposed surface of the polymer increases nickel coverage rates by afactor of at least about 2.5. When sulfur is included in thepolymercarbon black compositions and not merely in the very surfacelayer as in the materials of Series II Table 1, rates of nickel coveragecan be much higher. For example, with a composition containing 100 partsby weight nitrile rubber, 50 parts by weight acetylene black and 4 partsby weight sulfur, nickel coverage rates at 3.0 volts of over 6 cm/min.can be obtained. The rate of nickel coverage increases linearly withincreases in voltage. Using a composition containing a weight ratio of 2to l of nitrile rubber to acetylene black and 2.5% by weight of sulfurbased upon the weight of rubber, a nickel coverage rate of about 9.5cm/min. was obtained at a voltage of 3.0 and a rate of about 14.7cm/min. at a voltage of 4.5. It is important that the sulfur present inthe polymer-carbon black compositions be in the form of non-ionicsulfur, i.e., that. it not be tied up as a metal sulfide or in a stableion such as the sulfate ion. Ordinarily, elemental sulfur is used but,if desired, sulfur in the form ofa sulfur donor such as sulfur chloride,2-mercapto-benzothiazole, N- cyclohexyl-2-benzothiozole sulfonomide,dibutyl xanthogen disulfide and tetramethyl thiuram disulfide orcombinations of these and sulfur can also be employed. Those skilled inthe art will recognize that these sulfur donors are the materials whichhave been used or have been proposed for use as vulcanizing agents oraccelerators.

The advantage obtained when sulfur is included in the polymer-carbonblack surface is dramatically depicted in the drawing. Referring nowthereto both FIGS. 1 and 2 depict indenticalacrylonitrile-butadienestyrene plaques 11 coated with polymer-carbonblack coating 12 containing 20 parts by weight of neoprene and 10 partsby weight of acetylene black and having a wire contact 13.

The coating 12 of FIG. I initially contained a small amount of thiuramand was treated with a 1% by weight solution of sulfur in cyclohexaneprior to plating so as to incorporate a small effective amount of sulfurin the coating. Coating 12 of FIG. 2 was made with a neoprene free ofthiruam, was not exposed to a sulfur solu tion and therefore containedno sulfur. Both plaques were made cathodic under identical voltageconditions (3 volts closed circuit cell potential) in the same nickelplating bath. After 1 /2 minutes the area 15 above line 14 in FIG. 1 wasuniformly coated with a highly adherent nickel deposit. At this time theplaque .was removed from the plating bath. If it were not removed fromthe bath, the plating front, as depicted by line 14, would continuedownwardly across plaque 11 of FIG. 1 until, at the end of about 5minutes the whole plaque would be coated with a firm, adherent, evendeposit of nickel. In contrast, the plaque of FIG. 2,. after 20 minutesin the plating bath, had a loosely adherent fern-like deposit on thearea external of closed, irregular curves l6 and 17 leaving sulfur'freecoating 12 exposed internally of closed irregular curves 16 and 17. Acomparison of FIGS. 1 and 2 of the drawing clearly shows that platingpractice in accordance with the present invention is highlyadvantageous.

The cathodic electrolytic treatment used according to the presentinvention to induce nickel coverage across the expanse of polymer-carbonblack mixture surface is carried out in an electrolyte bath from whichnickel can be deposited and which, ordinarily is aqueous and containsabout to about grams per liter (gpl) of nickel ion, complementing anionfrom the group of sulfate, chloride, sulfamate, fluoborate and mixturesthereof and exhibits a pH of about 2.8 to about 4.5 stabilized byinclusion of a buffer such as boric acid in the bath. An ordinary Wattsbath is quite satisfactory for use both as'the initial bath for nickelcoverage and for subsequentt plating. If desired, after nickel coveragehas been established, one can plate in a nickel bath containing any kindof additive, e.g., levelling agents or brightening agents, etc., knownto the art. Further, after nickel coverage is established one can platenot only with nickel but also with any other electrodepositable metalcompatible with nickel, e.g., chromium, copper. zinc, tin, silver, gold,platinum, palladium, cadmium etc.

The cathodic treatments in accordance with the invention to induce thegrowth of iron or cobalt across the polymer carbon-black surface can becarried out in any electroplating bath from which these metals can bedeposited. For example, the process of the invention has been carriedout using an aqueous ferrous chloride bath to deposit iron and anaqueous cobalt chloridecobalt sulfate bath to deposit cobalt. Details ofoperation for these and other iron, cobalt and nickel baths can beobtained from any text on electroplating, for example, ElectoplatingEngineering Handbook, edited by A. Kenneth Graham, Reinhold PublishingCorporation, Copyright 1955. Those skilled in the art will appreciatethat for particular purposes it may be advantageous to deposit alloys ofnickel, cobalt and iron such as ironnickel alloys, nickel-cobalt alloysetc.

In addition to iron, nickel and cobalt, other metals of Group VIII ofthe Periodic Table of Elements can be deposited in the manner asdepicted in FIG. 1 of the drawing, that is initially behind a depositionfront moving across the polymer-carbon black surface. In particularpalladium has been found to spread across a polymer-carbon black surfaceat a rate roughly equivalent to the rate at which iron spreads, whichrate is somewhat slower than the spreading rate of nickel and cobalt allother conditions being equal.

While the present invention is especially concerned withelectrodeposition of metal on a wide variety of plastic and othernon-conductors (and on other materials which are not generally amenableto ordinary electroplating techniques) using a coating techniqueinvolving an essentially solid polymer carbon-blacksulfur-containigcoating adhered directly or through an intermediate layer onto a base,the invention is also applicable to bases having the requisite carbonblackpolymer-sulfur composition. As an example, a sample of EPDMsynthetic rubber having a volume resistivity of about 235ohm-centimeters and containing reinforc ing type, furnace carbon blackand sulfur is directly plateable in a Watts-type nickel bath to providea highly adherent, rapidly formed overall deposit of nickel. Thespreading of the deposit from a point of metallic conduction differssomewhat in the case ofa solid base of polymer-carbon black-sulfur fromthe spreading depicted in FIG. 1 of the drawing which is typical ofmetal spreading using coatings. With a solid polymer-carbon black-sulfurbase the electrodeposited metals tends to rapidly film over the entiresurface of the object blurring to a certain extent the metal depositionfront depicted in FIG. 1 of the drawing.

In order to give those skilled in the art a better understanding andappreciation of the invention the following examples are given:

EXAMPLE I A coating formulation was made up as follows:

6 (1) Product of Uniroyal Chemical, Naugatuck, Conn.

(2) Product of Shawinigan Products Corp., Englewood Cliffs, NJ.

The aforedescribed coating formulation was sprayed on anacrylonitrile-butadiene-styrene (ABS) surface to provide a dried coatingabout 0.0025 cm. thick. The coated and dried ABS surface was thenexposed for 40 seconds to the vapor above sulfur monochloride held atroom temperature (about 25C). The surface having a single metal contactwas'then placed in a Watts-type nickel plating bath as a cathode with adriving voltage of about 3 volts in opposition to a nickel anode. Thenickel deposit grew rapidly across the coated ABS surface and depositionwas continued until the deposited nickel had a substantially uniformthickness of about 0.0025 cm. The electrodeposit showed a 90 peelstrength of about 1.88 kilogram per centimeter (kg/cm) width (10.5 lb/inwidth) when pulled at 2.54 cm/minute.

EXAMPLE II The following coating formulations were prepared:

Products of Uniroyal Chemical, Naugutuck. Conn.

Coating A was applied by brushing onto a poly-(vinyl chloride) (PVC)plaque, and then coating B was applied in similar fashion over the driedcoating A. After curing in an air oven for 3 hours at 90C. the plaquewas dipped into a l w/o solution of sulfur in cyclohexane, then platedto a thickness of about 0.001 inch with Watts nickel. Initially thenickel deposit grew rapidly across the surface of the plaque from asingle metal contact. A 90 peel strength of 2.5 kg/cm l 2 lb/in) wasachieved for the electrodeposit.

EXAMPLE Ill The following coating formulations were prepared:

Coating C Material Parts-by-Weight Neoprene AF 50 Neozone D l Magnesia 2Zinc Oxide 2.5 5 Alkyl Phenolic Resin (SP-I36) 20 Ethyl Acetate -80Hexane 82 Toluene 81 Water 0.5

-Continued Material Parts-by-Weight Coating D Material Parts-by-WeightAcetylene Carbon Black Natural Rubber (Smoked Sheet) 7.5 StyreneButediene Rubber (Naugapel 7.5

(I503) Sulfur 0.9 Heptane 240 Turpentine 70 Trichloroethylene 75Products of E. l. Dupont de Nemours and Co. Product of SchenectadyChemical lnc., Schenectady. N.Y. Product of Uniroyal Chemical.Naugatuck. Conn.

An ABS panel was dipped in coating C, air dried, then dipped intocoating D, and again air dried. it was then directly electroplated in aWatts bath and the resulting nickel electrodeposit had a 90 peelstrength of 1.79 kg/cm of width (10 lb/in.).

EXAMPLE IV Coatings A and B from Example 11 were modified so that theconcentration of curatives (CP-B, Ethazate, D-B-A and sulfur) wasdoubled. In addition, MEK was added to coating A such that its finalweight equaled that of the xylene (i.e., from 11.3 to 77.5). An ABSpanel was successively dipped in modified coating A, then into modifiedcoating B. The panel was cured at 85C for 1 /2 hours, during which timea noticeable sulfur bloom appeared on the surface. The panel was thendirectly electroplated with Watts nickel with a rapid initial rate ofcoverage. The resulting metal deposit exhibited a 90 peel adhesion ofabout 3.58 kg/c m of width lb/in).

EXAMPLE V An ABS panel (Cycolac standard test plaque) was coated bysuccessively dipping in first coating A, then coating B of Example 11.After curing 15 hours in air at 85C, the panel was dipped into a l w/osolution of sulfur in cyclohexane. It was then plated with a WattsFLASH, 0.0009 inch of semibright (Perflow) nickel, 0.0003 inch of bright(Udylite) nickel and 15 p. in conventional chromium. The plated panelwas given a thermal cycle of 90C for 2 hours, room temperature for 1hour, 40C for 2 hours, and then given a 16-hour exposure to CASStesting. No detectable failure resulted on the panel from thistreatment.

Those skilled in the art will appreciate that although in most of theforegoing examples ABS plastic plaques were used, the process of thepresent invention is equally as well adapted to the electroplating ofutilitarian and decorative objects made of other plastics such aspolystyrene, phenol formaldehyde resins, ureaformaldehyde resins,polyacrylates and methacrytates, polyurethane, silicones, vinyls,vinylidenes, epoxys, polyolefins and similar thermoplastic andthermosetting resinous materials. In addition, the process of thepresent invention can also be used to plate metals which are coated withnon-metallic, non-electrically conductive coatings, e.g., varnishedaluminum and the like. Those skilled in the art, in considering thescope of utility of the process of the present invention, will recognizethat with some base materials it will be necessary to include anadhesive layer between the polymer carbon black plating substrate andthe particular base material. While the form and character of the basematerial is not of significance to the operability of the process of thepresent invention, particular base materials can provide qualities ofutility not ordinarily contemplated. For example, a loosely matted paperwas coated with a polymer-carbon black-sulfur mixture to provide aftermetal deposition a novel useful electrode skeleton for a battery plaque,fuel cell electrode or the like. In this regard special attention isdirected to the deposition of precious metals from Group VIII. Whileeconomic factors make it unlikely that platinum, palladium, rhodium,iridium, ruthenium and osmium would find much use in the decorativeplating of plastics. these metals can be usefully deposited in the formof electrodes, catalysts, etc., where their particular chemical andelectrochemical characteristics can be utilized.

EXAMPLE VI A sample plastic treated and coated as in Example 111 wasimmersed as a cathode in an aqueous plating bath containing 300 gpl offerrous chloride, 150 gpl of calcium chloride adjusted to a pH of 1.2 to1.8 and held at a temperature of about 87C. Upon passage of currentthrough the bathat a voltage of 6 volts, the surface of the samplebecame covered with a smooth adherent coating of iron.

EXAMPLE VII The sample of Example V] was. immersed as a cathode in anaqueous cobalt plating bath containing about 335 gpl of cobalt sulfate,about 74 gpl of cobalt chlo ride, about 46.5 gpl of boric acid and about1.2 gpl of sodium fluoborate. Upon passage of current through the bath,the sample rapidly filmed over with cobalt.

EXAMPLE Vlll One hundred parts by weight of a low-density, generalpurpose polyethylene were milled in a Banbury type mixer at atemperature of about 178C. along with 50 parts by weight of Vulcan XC72carbon black (supplied by Cabot Corporation) and Tetrone A branddipentamethylenethiuram hexasulfide. The milled composition was thenmolded and the molding thus produced was inserted as a cathode in anickel plating bath. Nickel rapidly spread over the surface from ametallic point of contact and plating was continued to provide a firm,adherent nickel electrodeposit having a peel strength of about 1.8 kg/cmof width.

Although the present invention has been described and illustrated inconjunction with preferred embodiments, it is to be understood thatmodifications and variations may be resorted to without departing fromthe spirit and scope of the invention. For example, those skilled in theart will appreciate that the molding composition upon which nickel wasdeposited in Example Vlll is illustrative of a broader range ofpolyethylene, polypropylene and mixtures and copolymers thereof havingblended therein about 15% to about 60% by weight (of the totalcomposition) of carbon black, to give a volume resistivity of less thanabout 1,000 ohm-centimeters, along with sulfur or a sulfur donor forexample of the dipentamethylenethiuran hexasulfide type in an amountequivalent in sulfur content to about 1% to about 10% by weight (of thetotal composition) of dipentamethylenethiuram hexasulfide. In platingmassive polymer bodies as in Example Vlll an interesting phenomenon hasbeen noted, that is, the bond strength of nickel'electrodeposited on thepolymer surface improves with aging at room temperature. Thus the 90peel strength set forth in Example VIII is the peel strength observedimmediately after plating. After a few days aging the observed bondstrength is often double (or more) of that strength as set forth inExample VIII. Such compositional and processing modifications andvariations are considered to be within the purview and scope of theinvention and appended claims.

I claim:

1. A process for metallizing comprising (1) introducing an essentiallysolid surface in contact with a metallic conductor into anelectroplating bath from which a metal from the Group VIII of theperiodictable and alloys thereof can be plated; (2) said essentiallysolid surface comprising an intimate mixture of an organic polymerreactive with sulfur, a carbon black and a substance from the group ofsulfur and sulfur donors and having a volume resistivity of less thanabout 1,000 ohm-centimeters and (3) applying a potential to said surfacethrough said metallic conductor to cause metal from said group todeposit upon said surface in an essentially uniform manner from thelocus of said metallic conductor.

2. A process as in claim 1 wherein the metal is from the group of iron,nickel and cobalt.

3. A process as in claim 2 wherein the polymer is an elastomer.

4. A process as in claim 2 wherein the carbon black is a conductivecarbon black and the surface material has a volume resistivity of aboutI to about ohmcentimeters.

5. A process as in claim 2 wherein the potential is in excess of about0.2 volt cathodic.

6. A process as in claim 2 wherein the metal deposited is from the groupof nickel and cobalt.

7. A process as in claim 6 wherein the metal deposit is nickel.

8. A process as in claim 3 wherein the elastomer is an unsaturatedelastomer.

9. A process as in claim 8 wherein the elastomer is polychloroprene.

10. A process as in claim 1 wherein the essentially solid surfacecontains a conductive carbon black and comprises a coating on asubstrate.

1 l. A process as in claim 10 wherein a metal from the group of iron,nickel and cobalt is deposited on said essentially solid surface.

12. A process as in claim 10 wherein the substrate is a non-conductor ofelectricity.

13. A process as in claim 12 wherein the substrate is a plastic.

14. A process as in claim 11 wherein the composition used to form thecoating contains sulfur.

15. A process as in claim 11 wherein the composition used to form thecoating is treated subsequent to coating formation to enrich the surfacethereof with sulfur.

16. A process as in claim 11 wherein the material of the coating has avolume resistivity in the range of about 1 to about 10 ohm-centimeters.

17. A process as in claim 10 wherein the metal deposited is from thegroup of cobalt and nickel.

18. A process as in claim 17 wherein the metal deposited is nickel.

19. A process as in claim 17 wherein the metal deposited on said surfacespreads rapidly across said surface behind a sharply defined platingfront.

20. A process as in claim 10 wherein the solid surface contains anelastomer.

21. A process as in claim 20 wherein the elastomer is an unsaturatedelastomer.

22. A process as in claim 21 wherein the unsaturated elastomer ispolychloroprene.

23. A process as in claim 12 wherein the substrate is a fiberousaggregation.

24. A process as in claim 1 wherein said essentially solid surface isthe surface of a mass having an essentially uniform compositiontherethrough.

25. A process as in claim 24 wherein the uniform composition includes anelastomer.

26. A process as in claim 24 wherein nickel is deposited on saidessentially solid surface.

27. A process as in claim 24 wherein the uniform composition includespolyethylene or polypropylene.

28. A process as in claim 25 wherein the elastomer is anethylene-propylene terpolymer.

29. A process as in claim 27 wherein the final electrodeposit is aged onsaid uniform composition to increase the adhesion of said deposit tosaid composition.

1. A PROCESS FOR METALLIZING COMPRISING (1) INTRODUCING AN ESSENTIALLY SOLID SURFACE IN CONTACT WITH A METALLIC CONDUCTOR INTO AN ELECTROPLATING BATH FROM WHICH A METAL FROM THE GROUP VIII OF THE PERIODIC TABLE AND ALLOYS THEREOF CAN BE PLATED; (2) SAID ESSENTIALLY SOLID SURFACE COMPRISING AN INTIMATE MIXTURE OF AN ORGANIC POLYMER REACTIVE WITH SULFUR, A CARBON BLACK AND A SUBSTANCE FROM THE GROUP OF SULFUR AND SULFUR DONORS AND HAVING A VOLUME RESISTIVITY OF LESS THAN ABOUT 1,000 OHM CENTIMETERS AND (3) APPLYING A POTENTIAL TO SAID SURFACE THROUGH SAID METALLIC CONDUCTOR TO CAUSE METAL FROM SAID
 2. A process as in claim 1 wherein the metal is from the group of iron, nickel and cobalt.
 3. A process as in claim 2 wherein the polymer is an elastomer.
 4. A process as in claim 2 wherein the carbon black is a conductive carbon black and the surface material has a volume resistivity of about 1 to about 10 ohm-centimeters.
 5. A process as in claim 2 wherein the potential is in excess of about 0.2 volt cathodic.
 6. A process as in claim 2 wherein the metal deposited is from the group of nickel and cobalt.
 7. A process as in claim 6 wherein the metal deposit is nickel.
 8. A process as in claim 3 wherein the elastomer is an unsaturated elastomer.
 9. A process as in claim 8 wherein the elastomer is polychloroprene.
 10. A process as in claim 1 wherein the essentially solid surface contains a conductive carbon black and comprises a coating on a substrate.
 11. A process as in claim 10 wherein a metal from the group of iron, nickel and cobalt is deposited on said essentially solid surface.
 12. A process as in claim 10 wherein the substrate is a non-conductor of electricity.
 13. A process as in claim 12 wherein the substrate is a plastic.
 14. A process as in claim 11 wherein the composition used to form the coating contains sulfur.
 15. A process as in claim 11 wherein the composition used to form the coating is treated subsequent to coating formation to enrich the surface thereof with sulfur.
 16. A process as in claim 11 wherein the material of the coating has a volume resistivity in the range of about 1 to about 10 ohm-centimeters.
 17. A process as in claim 10 wherein the metal deposited is from the group of cobalt and nickel.
 18. A process as in claim 17 wherein the metal deposited is nickel.
 19. A process as in claim 17 wherein the metal deposited on said surface spreads rapidly across said surface behind a sharply defined plating front.
 20. A process as in claim 10 wherein the solid surface contains an elastomer.
 21. A process as in claim 20 wherein the elastomer is an unsaturated elastomer.
 22. A process as in claim 21 wherein the unsaturated elastomer is polychloroprene.
 23. A process as in claim 12 wherein the substrate is a fiberous aggregation.
 24. A process as in claim 1 wherein said essentially solid surface is the surface of a mass having an essentially uniform composition therethrough.
 25. A process as in claim 24 wherein the uniform composition includes an elastomer.
 26. A process as in claim 24 wherein nickel is deposited on said essentially solid surface.
 27. A process as in claim 24 wherein the uniform composition includes polyethylene or polypropylene.
 28. A process as in claim 25 wherein the elastomer is an ethylene-propylene terpolymer.
 29. A process as in claim 27 wherein the final electrodeposit is aged on said uniform composition to increase the adhesion of said deposit to said composition. 